Optical masks are used in fabrication of a variety of electronic devices, including magnetic recording transducers. For example, FIG. 1 depicts air-bearing surface (ABS) view of a conventional perpendicular magnetic recording (PMR) transducer 10 used in recording a PMR media (not shown). The conventional PMR transducer 10 is typically used as a write head in a merged head including the conventional PMR transducer 10 and a read head. The conventional PMR transducer 10 includes a conventional first pole (P1) 12, insulator 14, insulator 16, a conventional PMR pole (main pole) 18, write gap 20, and shield 22. The PMR pole 18 has a negative angle, φ. Thus, the top of the conventional PMR pole 18 is wider than the bottom of the PMR pole 18.
FIG. 2 depicts a conventional optical mask 30 for fabricating a portion of an electronic device, such as the conventional pole 18 of the conventional PMR transducer 10. The conventional optical mask 30 is used to transfer the pattern of the conventional optical mask 30 to a photoresist mask, and thus to the conventional PMR transducer 10. The conventional optical mask 30 has a shape corresponding to the shape desired to be developed. Consequently, the optical mask 30 includes a region 32 corresponding to a nose region, corners 34A and 34B, and a flare angle, φ. The region 32 might be transparent, while the remaining regions are opaque. In another implementation, the conventional optical mask 30 may be opaque in the region 32 and transparent in the remaining regions.
FIG. 3 depicts a conventional resist mask 40 formed using the conventional optical mask 30. A layer of resist (not shown) is typically spun onto the surface of the conventional PMR transducer 10. The photoresist layer is developed using the conventional optical mask 30 to block a portion of the light used as well as light of the appropriate wavelength. The conventional resist mask 40 is developed from the layer of photoresist. Because of the use of the conventional mask 30, the conventional resist mask 40 includes a trench having a nose region 42 and arcs 44A and 44B. The conventional resist mask 40 covers a portion of the conventional PMR transducer 10 during fabrication, allowing the conventional PMR pole 18 to be formed therein.
FIG. 4 depicts a top view of a portion of the conventional pole 18. Near the ABS, the conventional PMR pole 18 terminates in a nose 19. The conventional PMR pole 18 thus flares outward from the nose 19 at a flare angle, φ, forming corners 21A and 21B. The flare angle, φ, is typically desired to be approximately one hundred and fifty degrees.
Referring to FIGS. 1-4, although the conventional mask 30 and conventional resist mask 40 may be used to form the conventional PMR pole 18, there are drawbacks. In particular, the shape of the nose 19 may not be well controlled. Although the conventional mask 30 includes relatively sharp corners 34A and 34B, the corresponding regions of the conventional resist mask, arcs 44A and 44B, are rounded. It is believed that this rounding is due to optical proximity effects during exposure of the resist mask 40. Even though the desired obtuse angle, φ, may be achieved, the rounding adversely affects the PMR pole 18. Because of the rounding in the regions 44A and 44B, the conventional PMR pole 18 also has rounded corners 21A and 21B, respectively. Rounding of the corners 21A and 21B results in variations in the nose 19. For example, variations in the write track width and shape of the pole 18 may result. Consequently, performance of the PMR transducer 10, as well as the performance of other electronic devices also desired to have sharper corners, may suffer.